Generation of a novel monoclonal antibody WMab-1 specific for IDH2-R172W mutation

Isocitrate dehydrogenase 2 (IDH2) mutations have been detected in gliomas, cartilaginous tumors, and acute myeloid leukemias. IDH2 mutations are specific to a single codon in the conserved and functionally important Arginine 172 (R172) or Arginine 140 (R140). To date, we have established specific monoclonal antibodies (mAbs) against IDH2-R172K and IDH2-R172M. However, specific mAbs against IDH2-R172W have not been reported. To establish IDH2-R172W-specific mAbs, we immunized rats with IDH2-R172W peptides. Western-blot analysis showed that WMab-1 reacted with the IDH2-R172W recombinant protein, not with IDH2-wild type (WT) or other IDH2 mutants, indicating that WMab-1 is IDH2-R172W-specific. Furthermore, WMab-1 specifically stained the IDH2-R172W-expressing cells in immunocytochemistry, but did not stain IDH2-WT and IDH2-R172M-containing cells. WMab-1 also specifically stained the IDH2-R172W-expressing glioma cells in immunohistochemistry. This is the first report to establish an anti-IDH2-R172W-specific mAb, which could be useful in the diagnosis of IDH2-R172W-bearing tumors.